Electromagnetic switch insensitive to position orientation



Aug. 11,1970 A. J. GRENIER ELECTROMAGNETIC SWITCH INSENSITIVE TO POSITION ORIENTATION Filed July 22, 1968 8 Sheets-Sheet 1 N Q Q ,3 l I ll/ la I on;

" lll' Inventor, Avme J. Grenzer,

43 Amqly.

Aug. 11, 1970' A. J. GRENI'ER' ELECTROMAGNETIC SWITCH INSENSITIVE TO POSITION ORIENTATION Filed July 22, 1968 8 Sheets-Sheet 2 Inventm;

- I Aime'r]. Grenier,

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Aug. 11, 197% 3,524,154

ELECTROMAGNETIC SWITCH INSENSITIVE 'I'O POSITION ORIENTATION Filed July 22, 1968 A. J. GRENIER 8 Sheets-Sheet 5 1 Mi mmx p lmwemtam Awm 1-]: firamiew;

Filed July 22. 1968 Aug. 11, 1970 Q GREN|ER 3,524,154

I ELECTROMAGNETIC SWITCH INSENSITIVE TO POSITION ORIENTATION 8 Sheets-Sheet 4.

Inventor, Atme J Grenzer;

Aug. 11, 1970 4 A, J. GRENIER 3,524,154

ELECTROMAGNETIC SWIT CH INSENSITIVE TO POSITION ORIENTATION Filed July '22, 1968 8 Sheets-Sheet 5 F'QJ'. ,0

III" l Inventor; Azme r]. Grenier Q ELECTROMAGNETIC SWITCH INSENSITIVE TO POSITION ORIENTATION Filed July 22, 1968 A. J. GRENIER Aug. 11, 1970 8 Sheets-Sheet 7 Alan I. DID I V Y H x a? T Q mS I Inventor, Awme JI G'reni/er, b

United States Patent 3,524,154 ELECTROMAGNETIC SWITCH INSENSITIVE T0 PDSITION ORIENTATION Aim .I. Grenier, North Attleboro, Mass, assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed July 22, 1968, Ser. No. 746,521 Int. Cl. H0111 1/22 U.S. Cl. 335200 14 Claims ABSTRACT OF THE DISCLOSURE A switch useful for starting motors comprising a housing mounting a solenoid, a pivotally mounted balanced armature assembly having three legs, two of which form with the solenoid core and armature body the magnetic circuit of the switch. The third leg mounts a variable rate spring and a bn'dging contact plate which in turn mounts a pair of movable contacts. A second spring, mounted on a calibration screw accessible outside the housing, biases the armature in a contacts open direction.

This housing cover biases a flexible projection on the solenoid spool to securely retain it in the housing. The core configurations are disclosed for the solenoid.

Among the objects of the invention is the provision of a switch which is compact, simple in design, capable of operation over a relatively wide range of operating parameters, and one which is easily manufactured and assembled in final operative condition.

A further object of the invention is the provision ofa switch which can be mounted without regard to posi tion orientation and can be conveniently calibrated from without the housing and a device which can switch higher current levels than prior art devices.

This invention is an improvement of my invention disclosed and claimed in US. Pat. 3,192,340, issued June 29, 1965, assigned to the assignee of the instant invention. A switch constituted according to the present invention is considerably less expensive to produce while being capable of handling higher current levels and useful with a wider current range.

In the drawings, FIG. 1 is a plan view of a switch made in accordance with the invention with the cover removed.

FIG. 2 is a view similar to FIG. 1 but with thearmature and contact plate removed and a portion of the armature and coil shown in sections.

FIG. 3 is a sectional view of the FIG. 1 switch taken on line 33 of FIG. 1 shown with the armature in the contacts open position.

FIG. 4 is a sectional view taken on line 4-4 of FIG. 3.

FIG. 5 is a sectional view taken on line 55 of FIG. 3.

FIG. 5 a shows a modified form of the armature pivotal mounting means of FIG. 5.

FIG. 6 is a sectional view taken on line 66 of FIG. 3.

FIG. 6a is a sectional view taken on line 6a6a of FIG. 6 and shows detail terminal structure.

FIG. 7 is a sectional view similar to FIG. 3 but with the housing in phantom lines and with the armature in the contacts closed position.

FIG. 8 shows the contact mounting arrangement employed in the device.

FIG. 9 is a perspective view of the armature of the switch.

FIG. 10 is a perspective view of a stationary contact and coil terminal assembly of the switch.

FIG. 11 is a partly schematic and partly pictorial view of an exemplary circuit diagram with which the switch shown in FIGS. 1-10 may be used.

3,524,154 Patented Aug. 11, 1970 Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Dimensions of certain of the parts as shown in the drawings may have been modified or exaggerated for the purposes of clarity of illustration.

Referring now to the drawings, especially to FIGS. 1, 3 and 5, an electrical switch embodying the instant invention takes the form of an electromagnetic relay generally indicated by the reference numeral 10, and includes a casing comprising a base 12 and a cover 14 made of a suitable moldable phenolic resinous material such as, for example, are resistant moldable phenolic resinous material. Switch 10 may be provided with suitable mounting means such as, for example, a mounting bracket 16 having a threaded aperture 18 through which extends a conventional threaded fastener 20. Base 12 is provided with a boss 22 having a bore 24 through which fastener 20 extends. Fastener 20 also extends through bore 24 in base 12 and bore 30 in cover 14, securing cover 14 to base 12 and both members to mounting bracket 16. In some instances it may be desirable not to use mounting bracket 16 in which event a nut (not shown) may be placed in recess 32 of cover 14 to cooperate With fastener 20 in securing cover 14 to base 12. Base 12 is provided with an annular flange 26 which interfits with recess 28 of cover 14.

A coil 36 is wound on spool 38 formed of an electrical- 1y insulating material, preferably a flexible polymeric material such as nylon. Spool 38 has end flanges 40a, 40b. Flanges 40a, 40b are each provided with projectingportions 42a, 4212 respectively, so that cover 14 biases the spool firmly into position in base 12. See FIG. 3 in which it is indicated how that portion of the flange is deformed. Apertures 44a, 44b provide even greater flexing to the projecting portions 42a, 4212.

Core member 46 of any good magnetic material is formed with ear portions 48a, 48b. Ribs 50 may be formed in base 12 to firmly secure core 46 in place. An armature 52 having a bight portion 54 and legs 56a, 56b, 58 extending in generally parallel directions. Body portion 54 and legs 56a, 56b are generally U shaped and cooperate with core 46 to form the magnetic circuit of the switch. Pintles 60a, 60b are located in body portion 54 and received in seat portions 62a, 621) respectively, in base 12, to pivotally mount armature 52 in switch 10 so that legs 56a, 56b can move toward and away from core 46, thereby efrectively closing and opening the magnetic circuit. It will be seen that when leg members 56a, 56b approach the core, they fit into mating recesses defined by ears 48a, 48b of the core optimizing the magnetic circuit.

Extending from armature body 54 in a parallel but opposite direction from legs 56a, 56b is the third leg 58 with a hole 64 provided in the distal end thereof. A stem 66 is slidably received in hole 64 and is provided with a head 68 having a convex shaped portion 70 which is seated in a countersunk portion 72 in hold 64 of leg 58, which portion in cross section may be either straight or concave (as shown in the drawings) in shape.

Contact plate 74 having an aperture 76 therein through which stem 66 extends is adapted to slide vertically within guide 78a, 78b, Sfla and 8% formed in base 12. Contacts 82a, 82b of a conventional good electrically conductive material such as fine silver or silver cadmiumoxide, are mounted on opposite distal end of contact plate '74. Contacts 82a, 82b may be formed with projections 84a, 84b therein to minimize contact resistance in the switch by increasing unit contact pressure and by making the contacts less sensitive to dust particles located on the contact surfaces. Stationary contacts 86a, 86b are mounted on extensions 88a, 88b of terminals 90, 92 respectively.

Terminals 90, 92 are provided with shoulders 90a, 9211 which reference the terminals with the bottom wall of base 12 so that the fixed contacts 86a, 8611 will be located in a desired location. Terminal 92 is provided with a leg 94 the function of which will be explained infra. An eyelet 96 is crimped onto stem 66 mounting in the stern variable rate spring 98 which biases contact plate 74 upwardly toward the fixed contacts. It will be noted that guides 78a, 78b and 80a, 8012 form a vertical guideway in which contact plate 74 moves toward and away from fixed contacts 86a, 86b. The convex surfaces 70 of head 68 contacting countersink surface 72 of leg 58 permits an etficient translation of rotary movement of the armature to the linear movement of contact plate 74. Movement of plate 74 is limited by the stationary contacts 86a, 86b in one direction and surfaces 100a, 100b of base 12 in the other direction (best seen in FIGS. 6 and 8). Base 12 is provided with a cavity 67 to permit movement of stem 66 between these positions.

Ribs 102a, 1102b are provided in base 12 to prevent tracking on the occurrence of arcing by providing an arc shadow and to increase oversurface clearance between terminal members 90 and 92.

Arm 58 is biased downwardly (in a clockwise contact opening direction) by a spring 104 which is attached at one end around neck 106 of leg 58 and at the other end by flange 108 formed on threaded member 110 which is mounted in bore 112. A conventional nut 114 cooperates with member 110 to permit adjustment of the amount of bias which is placed on armature 52 via leg 58.

The electrical circuit in the switch may be traced as follows: terminal 92, leg 94, lead 116 from coil 36 which lead is connected in any suitable way to leg 94- as by soldering; coil 36, lead 118 of coil 36 which is attached in a conventional manner as by soldering at 120 to platform 122 of terminal 124 (see FIG. 7).

Among the modifications which can be effected, armature 52 may employ pintles formed of a low friction polymer such as an acetal resin. Further, it may be desirable to eliminate ears 46a, 4612 from core 46 to preclude chattering of armature legs 56a, 56b on high overcurrent levels. Further, various types of terminal configurations can be employed, such as screw, quick-connect, and the like. A fourth terminal can be provided when it is desired to electrically isolate the coil and contact circuits.

One possible use of switch 10 would be as a motor starting relay shown in the circuit diagram of FIG. 11. The motor has a main winding W and a start winding W One end of winding W is connected to terminal 124 by conductor 126. The other end of winding W has a common connection with one end of winding W and is connected by conductor 128 with line L2, one side of a power source. The other end of winding W is connected by conductor 130 with terminal 90. Terminal 90 is electrically connected to terminal 92 through contact plate 74 and the associated contacts when relay coil 36 is energized at a current value above the minimum current required to cause armature 52 to move in a contacts closing direction. Terminal 92 is in turn connected to coil 36 by conductor 116 and to line L1 by conductor 132. 'When the circuit is energized, current will initially flow from line L1 to coil 36 through terminal 92 and main winding W through terminal 124 back through line L2. When power is just applied to the motor to main winding W then there is a relatively large inrush of current which energizes coil 36 to rotate armature 52 in a counter-clockwise or contacts closing direction. Closing of contacts 82a, 82b and 86a, 86b energizes the start winding W of the motor so that current flows from line L1 through terminal 92, contact plate 74 and associated contacts, terminal 90, conductor 130, the start winding and back to line L2 through conductor 128. As the motor speeds up, the current passing through main winding W and coil 36 decreases such that the biasing force exerted by spring 104 on armature 52 exceeds the magnetic force produced by coil 36 and urges the armature 52 in a contactsopening direction to quickly disconnect the start winding W Thereafter, current will continue to flow only in the main winding W until the motor is de-energized.

It will be seen from the foregoing that this invention provides a switch having a number of advantages including that of being substantially non-position sensitive due to the particular balanced armature assembly employed, particularly insensitive to vibration and shock, can handle greater current levels due to the double contacts which minimize contact welding possibility, is simplified from a construction viewpoint, yet providing simple calibration which is effected externally of the switch housing.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be made in the above const1uctions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense, and it is also intended that the appended claims shall cover all such equivalent variations as come within the true spirit and scope of the invention.

The double contact feature avoids the use of the conventional pigtail and permits higher current capacity since contact erosion and like problems are reduced. It will be seen that contact plate 74 is mounted such that even if one pair of contacts should weld, the other pair will still open to perform the switching function. Subsequent switching operation will then normally eventually break the welded pair. Spring 98 gives a soft or low spring rate at initial closure of the contacts and a stiffer or higher spring rate as the armature continues to rotate in a counter-clockwise direction. This permits the desired soft spring characteristics at low levels of coil energization and stiff spring characteristics at high levels of coil energization.

I claim:

1. A switch insensitive to mounting position comprising:

(a) a housing,

(b) an armature having a body portion from which exend three generally parallel legs, the first and second forming with the body a generally U configuration, the third leg extending in generally the opposite direction, two pintles extending from the body portion and received in recesses in the housing to pivotally mount the armature therein.

(0) a solenoid and core located in one end of the housing, the armature adapted to pivot so that the first and second legs move toward and away from the core,

(d) a stationary contact mounted in the housing,

(e) a first spring means and a contact plate mounted on the distal end portion of the third leg, a movable contact mounted on the contact plate and adapted to be biased by the first spring into engagement with the stationary contact when the first and second legs of the armaturemoves toward the core,

(f) a second spring means biasing the armature so that the first and second legs tend to move away from the core and maintain the contacts in an open condition; however, when sufficient electric current flows through the solenoid the first and second legs of the armature will move toward the core against the bias of the second spring means, forcing the movable contact on the'contact plate into engagement with the stationary contact, the first spring means applying a force on the contact plate. 2. The switch according to claim 1 in which the second spring means is attached to the armature intermediate the body portion thereof and the distal portion of the third leg.

3. The switch according to claim 2 including an adjustable member mounting the second means in the housing and in which access can be had from without the housing.

4. The switch according to claim 1 in which an aperture is provided in the distal end portion of the third leg and a pin is slidably mounted therethrough, the pin mounting therein the first spring means.

5. The switch according to claim 4 in which the aperture in the third leg is countersunk and the pin is provided with a head, a portion of which is formed in a convex configuration, forming a ball and socket joint.

6. The switch according to claim 1 in which the solenoid comprises a spool and coil wound thereon, the spool having two end portions, each provided with a flexible projection,

the housing comprises a base member and a cover member contacting and deforming the flexible projection, thereby firmly securing the solenoid in the base member.

7. The switch according to claim 1 in which the core is provided with recessed portions which receive the first and second legs of the armature.

8. The switch according to claim 7 in which a plurality of rib members are provided in the housing and adapted to contact the core on opposite ends thereof.

9. The switch according to claim 4 in which the contact plate is intermediate the first spring means and the third leg.

10. The switch according to claim 4 in which the contact plate is elongated having two opposite ends extending generally at a right angle to the third leg and mounting at each opposite end rnovable contacts, the housing mounting a pair of stationary contacts with which the movable contacts engage and disengage upon movement of the armature.

11. The switch according to claim 1 in which the first spring means include a variable rate spring.

12. The switch according to claim 1 in which the pintles are formed of low friction, polymeric material.

13. A switch comprising a housing, an elongated armature pivotally mounted generally intermediate the length thereof in the housing, the armature having a body portion from which extend three generally parallel legs, the first and second legs forming with the body a generally U-shaped configuration, the third leg extending in generally the opposite direction, a magnetizable core disposed in the housing adjacent one end portion of the first and second legs of the armature, an energizable coil surrounding the core, a contact plate carried by another end portion of the armature on the third leg, a pair of movable contacts disposed adjacent opposite ends of the contact plate on one side thereof, and a pair of spaced stationary contacts disposed in the case and engageable respectively by the movable contacts, the one end portion of the first and second leg of the armature being attracted toward the core upon energization of the coil to pivot the armature to a closed-contact position, and the pivotal axis of the armature being so disposed as to provide a substantially balanced armature and contact bar assembly with respect to pivotal movement about the pivotal axis, whereby the switch may be mounted in any position without substantially affecting the operating characteristics thereof.

14. A switch according to claim 13, including spring means having an end thereof connected to the armature and applying a force to the armature tending to move the first and second legs away from the core and maintain the contacts in an open position and a calibrating screw mounted in the housing, and connected to another end of the spring means.

References Cited UNITED STATES PATENTS 9/1942 Neuner 335-200 3/1947 Immel 335200 

